A source of illumination is used for lighting purposes. A linear light source may be used as a source of illumination to provide light in the backlights of display systems. In color transmissive display systems such as liquid crystal displays, the backlights are designed to provide light into the liquid crystal sheet. The light emanating from the liquid crystal sheet passes through a sheet of color filters. The color filter sheet allows only light of a particular color to pass through and blocks light of other colors. So, a significant proportion of light emanating from the backlight is blocked by the color filter sheet, reducing the efficiency of the display.
There exists prior art wherein a color display is lighted by column sources of light, each column carrying light of a particular color. A multicolored light source is needed so that light of various colors is coupled into the various columns. The multicolored linear light sources known in art are cumbersome and costly to produce. Thus, there is a need for a simple and cheaper multicolored linear light source.
A photoluminescent tube (usually known as a fluorescent tube) is used as a source of illumination for backlights in displays. A photoluminescent tube is made of a gas discharge tube coated with photoluminescent material on the surface of the tube. When a high voltage is applied across the tube, ionization of the gases occurs. These ions emit photons which hit the photoluminescent materials on the surface. The photoluminescent materials on the surface emit light of a particular spectrum. Photoluminescent material is any material which absorbs photons and hence emits photons. Photoluminescent materials include fluorescent materials, phosphorescent materials and scintillators.